The influence of tires on vehicle-driving safety has been the focus of the vehicle field and the public. Since the Tire Pressure Monitoring System (abbreviated to TPMS) became required to be included in the standard configuration of vehicles in the United States in 2003. TPMS has become a technical term with respect to the vehicle technology, and worldwide research, development and manufacturing of TPMS is rapidly increasing.
Referring to FIG. 1, the mainstream technical solutions of prior art TPMS 100 are: TPMS comprises two parts; remote tire pressure monitoring modules (abbreviated to RTPM) 1 installed within tires of a vehicle, and a central monitor 2 that includes an LCD display 150 installed in the driving cabin of a vehicle. Power is supplied by lithium thionyl chloride battery. The RTPM installed within each tire monitors and samples tire pressure and temperature therein, and transmits sampling data via high frequency radio wave (RF). Four or five (including spare tires) RTPM modules are included in one TPMS. The central monitor receives signals transmitted from the RTPM module and displays, in sequence, the data of pressure and temperature within each tire on the liquid crystal display panel for driver's reference. If abnormalities in tire pressure or temperature occur, the central monitor will generate different alerting signals to warn the driver to take necessary measures. The typical technical route or principle block diagram thereof is shown in FIG. 1, wherein,
The RTPM module 1 comprises a plurality of composite parts: 1) an intelligent sensor 102 having pressure, temperature, acceleration, voltage detecting, and post-signal processing ASIC chip assembly; 2) a 4-8 bits micro-computer control unit (MCU) 104; 3) a radio frequency transmission chip 106; 4) a lithium thionyl chloride battery 108; and 5) antennas 110.
The intelligent sensor 102, a system-on-chip module made by the technique of silicon micro-electro-mechanical system (MEMS) comprises a pressure sensor, a temperature sensor, an accelerometer, battery voltage detecting, an internal clock, and a digital signal processing ASIC unit having an analog-to-digital converter (ADC), sampling/holding (S/H), SPI ports, calibration, data management and ID code. The module is provided with mask programmability, which means that customers can use special software to configure the module.
The prior art TPMS technique supplies power for RTPM with lithium thionyl chloride battery, wherein as the RTPM is limited by battery capacity, the minimum power design of battery management adopts the solution of after-sampling dormancy and timing wake-up to meet the requirement that the service life of battery can last for 5˜10 years. In the manner of TPMS, pressure data, temperature data and the like are sampled at long intervals, in general, the sampling frequency of the pressure data is 1/3 Hz˜1/8 Hz and the data transmitting frequency is 1/30 Hz˜1/80 Hz, accurately controlled by the power management program of RTPM microprocessor. The interval of RTPM timing wakeup of RTPM is regularly set between the range of 3˜8 s. The RTPM module is in a state of dormancy during sampling intervals.
TPMS has a positive effect on keeping the tire in normal pressure, preventing and reducing accidents caused by tire bursts. However, as the sampling interval of the tire pressure data in the prior art TPMS system is as much as 3000˜8000 ms, thus there are certain limitations or deficiencies, wherein the system only has the function of indicating information of tire pressure and temperature, and the role the function plays is confined to warning and preventing, but cannot make a prompt response to tire burst or quick deflation and cannot provide effective help, which are features of the current TPMS technique. Strictly speaking, the prior art TPMS should be defined as an information indicating and warning system.
Relevant research materials show that a tire burst occurs suddenly, without any evident or definite signs beforehand, so that it cannot be avoided once and for all. The reasons for triggering a tire burst lie in that: the rising pressure and temperature within the tire, especially the friction inside the tire (between the rubber and the steel casing ply) induced by tire pressure that is too low leads to part of the rubber layer of the tire rising to a high temperature, Then the rubber and the casing ply begin stripping and embrittling, and finally brings on tire burst. Tire pressures that are too low and longtime high speed driving are significant inducements to tire burst.
The research report “3-Dimensional Simulation of Vehicle Response to Tire Blow-outs” published by Wesley D. Grimes—an American Scholar—shows that when a tire burst happens, the pressure within the tire is lost within 100 ms, thereby the rolling radius of the burst tire diminishes, and the rolling resistance increases to 30 times more than before bursting. The positive pressure Fz to the ground brought by the wheel with a burst tire and the wheel, that is diagonal to the wheel with the burst tire with the lateral friction subsequently declining. The process continues and thus the rim begins to roll the tire until the tire is torn and separated from the rim, so that the lateral friction drops rapidly. During the tire being rolled and torn, the rapid increase of rolling resistance between the tire and the ground causes the wheel to convert from rolling to sliding (when the wheel with a burst tire is a driven wheel), so that a lateral force is formed which impels the vehicle to move in a deviated driving direction.
Wesley D. Grimes' research report also shows that a simple tire burst will not inevitably cause an accident. Whether the driver makes an appropriate response to tire burst information or not and the specific conditions of the road where the vehicle is when a tire burst happens are directly linked to the occurrence of traffic accidents. In particular, over-steering and over-braking (brake dragging) will be likely to induce accidents. On the contrary, proper operation and control (adjusting and maintaining the driving path and braking moderately) will be likely to prevent accidents from happening.
The conclusion of the research report discloses an extremely significant fact: in the 2-3 seconds time from the tire burst occurrence, the driver is able to make a response. This response by the driver on the vehicle is considered to be necessary and indispensable, and plays a significant role in obviating the danger of tire burst.